Whenever it’s time for dinner, Xianbing or her husband always takes their 4-year-old daughter Sasha to play in the garden downstairs in the neighborhood. Shasha is a 4-year-old girl, fair skin, blonde hair, round face with a pair of big blue eyes. At first glance, she looks very much like a foreign girl, and the neighbors call her “doll”. Neighbors also praised Shasha’s education, never saw her eat snacks, and never ate what others gave her. Some neighbors also asked Xianbing how she raised her child to be so obedient. Xianbing sighed and said, “I don’t want Shasha to taste all the delicacies of the world like other children. However, when Shasha was 4 months old, I took her to the Children’s Hospital for a checkup because I felt that there was a strange odor in her urine, and it turned out that she suffered from phenylketonuria (PKU). The pediatrician told me that this disease will doom Shasha to become an “unappetizing” child before she becomes a teenager. Because the child’s body lacks the enzyme phenylalanine hydroxylase, it is unable to break down the phenylalanine in food, and phenylalanine is deposited in the body and affects the normal development of the child. Except for vegetables and plain water, they can’t eat almost anything we normally eat. After Sasha was examined for the disease, I had to wean her immediately as requested by the doctor. Sasha could only eat special phenylalanine-free milk powder, which we didn’t have at that time, so I had to ask someone to buy it from Beijing and send it back by mail. When Shasha could eat, I went to the Newborn Screening Center of the Maternal and Child Health Hospital to buy specially processed rice and noodles, which only contained starch and maltose but no protein. These things are very expensive, Sasha spends about 2,000 yuan a month just on food. Whenever she cooks, the child is given a small meal. First the child is fed, then she is taken outside to play and we adults eat in secret. We avoided the child when we ate, and we were even more afraid to let the child see the good things. For Shasha, many foods are “poison”. When my child was young and didn’t know any better, when she saw other children eating, Shasha often looked at me with pleading eyes and said, “Mom, I want to eat a mouthful of rice, even a little bit?” “Mommy, I want to eat a small piece of meat, just a little chew?” “Mommy, can I try some ice cream?” “Mommy, what does chocolate taste like?” …… But all of this is impossible to do, in order for Shasha to grow up like a normal child, I can only follow the doctor’s requirements to strictly control the child’s diet. Xian Bing said, tears in the eyes kept swirling. But the child can not eat, even a little bit, for children suffering from phenylketonuria, rice, pasta and other benzene amino acid food is “poison”, eat these things, their nervous system will be damaged, seriously affecting intellectual and physical development. Xianbing is pleased that, through the control of food this intervention, now Shasha development is basically normal, did not become mentally retarded or physically disabled children. Except for the different food, she is the same as normal children. Comment: Phenylketonuria is an autosomal recessive genetic disease, but also congenital amino acid metabolism disorders, the incidence of one in 10,000 in our country, the incidence of consanguineous marriages significantly higher. Clinical manifestations are mainly as follows: after several months of life, due to the lack of melanin synthesis, the affected children have yellowish hair, light skin color, light iris color, backward intellectual development, urine and sweat with rat urine odor, etc. Phenylalanine is the most common amino acid in human metabolism, and it is also a congenital amino acid metabolism disorder. Phenylalanine is one of the essential amino acids in human metabolism to supply the human body to synthesize thyroxine, adrenaline and melanin for various purposes. Under normal conditions, the body’s phenylalanine is oxidized to tyrosine under the action of phenylalanine hydroxylase. Tyrosine is the main component of lipoproteins in the central nervous system and plays an important role in the development of intelligence. Phenylketonuria babies, because the body lacks phenylalanine hydroxylase, so phenylalanine can not be oxidized into tyrosine, but only into phenylpyruvic acid, and in the blood and brain aggregation, and finally metabolized by the kidneys by the urinary excretion. Since phenylpyruvic acid has an aromatic odor, the baby’s diaper emits an odor. Phenylpyruvic acid in the brain in large quantities, but also make brain metabolism disorders, resulting in central nervous system damage, hindering brain development, resulting in children with mental retardation or even cause lifelong intellectual disability. At present, there is no specific drug for the treatment of this disease. Mainly rely on dietary control, including immediate weaning and stop using foods rich in phenylalanine, for infants can be fed to the special low-phenylalanine milk powder; for young children to add complementary foods should be starchy, vegetables and fruits and other low-protein foods; for children can be under the guidance of the doctor to use special food flour, lotus root powder, dates, potatoes, millet, lamb, cabbage, spinach and other food that does not contain or less contain phenylalanine. . The ideal time for dietary therapy is when the child is born, and the earlier the treatment, the better. Dietary therapy is continued until about 12 years of age, when the child’s brain tissue is maturing and has sufficient tolerance for a low-phenylalanine diet. Moreover, the maturing brain tissue is no longer sensitive to the damaging effects of phenylpyruvic acid. When the child grows up, he or she can basically live like a normal person. Couples with a family history of the disease are encouraged to have their fetuses prenatally diagnosed by DNA analysis or testing for pterin in amniotic fluid.